The number is blocked only by the number manager, i.e. the company that sold you the right to use the number. A number is usually never blocked without a very specific reason.
The service provider can block various services, i.e. incoming and outgoing calls (separately), message service, etc. Outgoing calls are usually blocked if there is a long-term arrears for payment of previous services, i.e. incoming calls and messages are preserved, only nothing can be sent out and no calls can be made, except for emergency calls, ie calls to special emergency calls number.
If you can make calls and send SMS/MMS, no one has blocked you. Other services are extremely rarely blocked.
So, if you can call out, no one has blocked you. It's that simple.